Gold to Bābākiam (4100)
- At the end of a syllable, the pharyngeal fricative ʕ disappeared and changed the previous vowel to a high tone. It also voiced the following consonant.
- Syllable-final k ḳ ŋ changed to kʷ ḳʷ ŋʷ. A few compound words in which the second element began with a vowel or a suppressed consonant split into doublets depending on whether the free (labiovelar) or bound (plain velar) version of the morpheme was generalized in the compound.
- In initial position, the labialized coronals tʷ dʷ nʷ shifted to t d n. Elsewhere, they decoupled to the sequences tu du nu.
- The bilabial approximant w changed to v (in internal reconstructions, also spelled "β") before a vowel.
- Then l lʷ both became w (not */v/) in all positions although it retained a rhotic allophone.
- NOTE ON POLITICS: Proto-Highland Poswa breaks off here.
- The labiovelar consonants kʷ ḳʷ hʷ gʷ became p ṗ f v unconditionally.
- Sequences of two vowels in which the first vowel was i or u became rising diphthongs. Then all clusters of a consonant followed by a semivowel came to be pronounced as coarticulated single consonants. Thus pua became pʷa, pia became pʲa, and so on. ñ was assimilated as nʲ.
- Stressed syllabic nasals were opened to sequences containing a schwa.
- The voiced fricative g assimilated to a neighboring glide /j/ or /w/, thus creating sequences of /jj/ and /ww/. The shift thus was gj jg gw wg > jj jj ww ww. This includes g after /ī/ and /ū/.
- The cluster dh shifted to ð.
- The voiced fricatives ð z g became silent between vowels and occasionally in initial position (due to compounding).
- NOTE ON POLITICS: This time period is around 3100 AD, near the beginning of the "Era of Happiness" (Yeisu Kasu: 3138 - 3302 AD). The branches of the language that fork off from mainline Bābākiam in 3138 all die out, and therefore all of their names in the history are written in Babakiam, but they could be revived as minor local languages, and there would be quite a lot of them.
- A voiced consonant in a cluster after a voiceless consonant (nearly always /p/ or /s/) disappeared. (This shift is responsible for important consequences in verb morphology in Poswa more than 5000 years later.) It was briefly /ʕ/.
- The voiced fricatives v z ž g changed to b d ǯ ġ before a high tone.
- The post-velar fricative consonants ħ ʕ, which had been developing labial compression, changed unconditionally to f v.
- The velar fricatives h g were fronted to š ž unconditionally. šʲ žʲ became š ž.
- The labialized voiced stops bʷ dʷ ǯʷ ġʷ changed to b.
- The palatalized voiced stops bʲ dʲ ǯʲ ġʲ changed to ǯ.
- Any remaining voiced stops b d ǯ ġ changed unconditionally to p t č k (except when in clusters).
- The voiced fricative žʷ changed to v.
- Tones were eliminated. However the stress accent (nouns on the penultimate syllable, verbs on the ultimate) remained and became regularized.
- The voiced stops d ǯ ġ (now found only in clusters) changed to n nʲ ŋ unconditionally.
- Remaining v changed to b.
- Remaining z changed to s.
- Newly created vowel sequences beginning with i or u collapsed into rising diphthongs, thus creating a new series of palatalized and labialized consonants.
- The labialized consonants bʷ žʷ changed to b unconditionally. (Despite the fact that a nearly identical sound change had occurred only shortly before this one, this rule was very common in verb forms that were created by the shift of /bua/ > /bʷa/ > /ba/, and likewise for other vowels.)
- The palatalized consonants bʲ žʲ changed to ž unconditionally. (The above shift also applies here; many verbs underwent a shift of /bia/ > /bʲa/ > /ža/.)
- A schwa ə in a word in which the following syllable had /a/ changed also to a. Note that this is the only vowel change in the entire history of the language going back 3500 years, even before the Gold language, except for a few diphthongizations such as /ua/ > /wa/. However, the vowel system became very unstable in the succeeding period as the language developed into Poswa and Pabappa.
- The stress was shifted to the first syllable in all words.